This invention relates to roller bearings, and more particularly to a roller bearing with an integrated seal.
Roller bearing seals are generally used to maintain a lubricant securely inside the bearing, and to prevent the penetration of foreign bodies into the bearing.
Roller bearing seals usually include an outer shield or covering and an inner sealing shield, the terms inner and outer referring to their relative axial position. Both kinds of seals are usually attached to the outer race of the bearing so that the inner race can turn relative to the seal. There is often a gap in the seal between the outer shield or covering and the inner race, to furnish the advantage of reduced friction, whereas the inner sealing shield generally makes contact with the inner race to furnish the advantage of greater sealing efficiency.
It is well known that a layer of grease in contact with a lip seal or a gap seal improves the efficiency of the seal. However, when a conventional sealed roller bearing turns at a high speed, it is normally not possible to maintain a thick layer of grease at the seal because the grease has a tendency to become ejected due to centrifugal force. Other known seals have axially circumscribed rims. However, the rims form either a labyrinth gap with the inner race, or they terminate with a sealing lip in contact with, or with no clearance from the inner race.
A problem that is common to these known devices is that in the space between the axial rims or lips and the sealing or inner shields it is not possible for a static layer of grease to form because of the very slight clearance from the inner race. With such a slight gap, the turbulent air currents which form around the rotating inner race break down the neighboring layer of grease, and prevent the build up of a layer of grease in front of the sealing gap. The layer of grease can only fulfill its function as an auxiliary seal if it remains static, and it can only remain static when the distance from the inner sealing shield to the rotating inner race is sufficiently great.
Previous attempts to improve the sealing efficiency of a roller bearing seal have often resulted in an increased amount of friction on the bearing, an unquestionably undesirable result. It is thus desirable to improve the efficiency of the covering and seal shields without increasing the amount of friction imposed on the inner race of a roller bearing due to the presence of such seals.